Common Infections Acquired During Hospital Stays

If you are having surgery, you may be concerned about a bacterial infection after your procedure. While these infections are often preventable with good wound care and frequent hand washing, some patients do experience an infection after surgery that can lead to long-term harm.

For most, a bacterial infection after surgery is relatively minor and leads to redness or pus in or around the incision. These infections are typically easily treated. More serious infections can be more challenging to treat and can lead to an extended hospital stay and serious illness. It is these more severe infections that enter the bloodstream, urinary or respiratory tract, and the infection may move outside of the surgical site or even begin in an unrelated part of the body.

Surgeons washing hands before surgery
Andersen Ross / Photographer's Choice / Getty Images 

Identifying Bacteria

Bacteria are tiny, so small that they cannot be identified without a microscope. To determine what type of bacteria is present in an ill patient, a sample of the body fluid suspected to be infected is taken. This fluid may be blood, urine, saliva, sputum or even a sample of fluid taken from the body during surgery. In order to better identify the bacteria, it is cultured, meaning the sample is placed in a petri dish and encouraged to grow. Once the bacteria ​grows for several days, the sample is much larger and can be placed under a microscope for identification.

Once the type of bacteria is identified, the sensitivity is determined. This means that the sample is exposed to different types of antibiotics, the one that damages the bacterial sample the most — the antibiotic the bacteria is most “sensitive” to — is typically the one used to treat the infection.

Hospital Acquired Infections

These infections typically begin in the hospital in the early days of recovery and, for that reason, are referred to as Hospital Acquired Infections. When these infections happen at the site of surgery they are referred to as Surgical Site Infections (SSI). These types of infections are typically treated with one or more IV antibiotics.

Some better-known hospital-acquired infections are:

Staphylococcus Aureus

Approximately one-third of Americans carry Staphylococcus Aureus, also known as “staph”, in their noses. Most people never know they are carrying the bacteria, as it causes no harm to most well individuals. When staph enters a surgical incision or another part of the body, it can cause a serious infection such as pneumonia. Staph is treated with antibiotics.

Methicillin Resistant Staphylococcus Aureus (MRSA)

MRSA is a type of Staphylococcus Aureus that has become resistant to Methicillin treatment. This means that a MRSA infection should not be treated by Methicillin or other members of the Penicillin family of antibiotics as it is able to resist the effects of these medications.

Vancomycin Resistant Staphyloccocus Aureus (VRSA)

VRSA is a type of Staphylococcus Aureus that has developed the ability to resist treatment with Vancomycin, a powerful antibiotic.


Enterococci is a bacteria that is typically part of the normal flora of the digestive tract and the female reproductive tract. When found in those locations, the enterococci is typically not harmful and plays a role in maintaining good health.

Vancomycin Resistant Enterococci (VRE)

VRE is a type of Enterococci that is resistant to treatment with Vancomycin. When found in an incision or the blood, VRE can quickly cause a very serious infection. 


This type of bacteria is naturally found in water and soil. It is typically not a problem for healthy individuals or even surgical patients, as an Acinetobacter infection is rarely found outside of the hospital setting. In fact, the individuals who are most likely to become ill with an Acinetobacter infection are individuals who are already dealing with an illness that is severe enough to require treatment in a critical care unit.


This is another type of bacteria that is not harmful when it is found in the gastrointestinal tract of a healthy person. An infection caused by Klebsiella is usually identified in a patient who is undergoing treatment that allows the bacteria to enter the body. Individuals who have a breathing tube, have venous access (such as an IV or central line), a ​foley catheter or have been recently treated with antibiotics are the most likely to develop a Klebsiella infection.

17 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. O’Brien WJ, Gupta K, Itani KMF. Association of postoperative infection with risk of long-term infection and mortalityJAMA Surg. 2020;155(1):61. doi: 10.1001/jamasurg.2019.4539

  2. Berríos-Torres SI, Umscheid CA, Bratzler DW, et al. Centers for Disease Control and Prevention guideline for the prevention of surgical site infection, 2017JAMA Surg. 2017;152(8):784.

  3. Anderson DJ, Podgorny K, Berríos-Torres SI, et al. Strategies to prevent surgical site infections in acute care hospitals: 2014 update. Infect Control Hosp Epidemiol. 2014;35(6):605-627. doi: 10.1086/676022

  4. Prasad S, Tyagi AK, Aggarwal BB. Detection of inflammatory biomarkers in saliva and urine: Potential in diagnosis, prevention, and treatment for chronic diseases. Exp Biol Med (Maywood). 2016;241(8):783-799. doi: 10.1177/1535370216638770

  5. Abayasekara LM, Perera J, Chandrasekharan V, et al. Detection of bacterial pathogens from clinical specimens using conventional microbial culture and 16S metagenomics: a comparative study. BMC Infect Dis. 2017;17(1):631. 10.1186/s12879-017-2727-8

  6. Khan ZA, Siddiqui MF, Park S. Current and emerging methods of antibiotic susceptibility testing. Diagnostics. 2019;9(2):49. doi: 10.3390/diagnostics9020049

  7. Voidazan S, Albu S, Toth R, Grigorescu B, Rachita A, Moldovan I. Healthcare associated infections—a new pathology in medical practice? International Journal of Environmental Research and Public Health. 2020;17(3):760. doi: 10.3390/ijerph17030760

  8. Surgical Site Infections: Prevention and Treatment. National Institute for Health and Care Excellence (NICE); 2020. PMID: 31211539

  9. Centers for Disease Control and Prevention. Healthcare Associated Infections (HAIs).

  10. Sakr A, Brégeon F, Mège JL, Rolain JM, Blin O. Staphylococcus aureus nasal colonization: an update on mechanisms, epidemiology, risk factors, and subsequent infections. Front Microbiol. 2018;0. doi: 10.3389/fmicb.2018.02419

  11. Self WH, Wunderink RG, Williams DJ, et al. staphylococcus aureus community-acquired pneumonia: prevalence, clinical characteristics, and outcomes. Clin Infect Dis. 2016;63(3):300-309.

    doi: 10.1093/cid/ciw300

  12. Sun L, Chen Y, Wang D, et al. Surgical site infections caused by highly virulent methicillin-resistant staphylococcus aureus sequence type 398, China. Emerging Infectious DiseasesJournal - CDC. 2019; 25 (1). doi: 10.3201/eid2501.171862

  13. Cong Y, Yang S, Rao X. Vancomycin resistant Staphylococcus aureus infections: A review of case updating and clinical features. Journal of Advanced Research. 2020;21:169-176. doi: 10.1016/j.jare.2019.10.005

  14. Krawczyk B, Wityk P, Gałęcka M, Michalik M. The many faces of enterococcus spp. —commensal, probiotic and opportunistic pathogen. Microorganisms. 2021;9(9):1900. doi: 10.3390/microorganisms9091900

  15. Gunalan A, Sivaradjy M, Priyadarshi K, Madigubba H, Rajshekar D, Sastry AS. Increasing trend of vancomycin-resistant enterococci bacteremia in a tertiary care hospital of south india: a three-year prospective study. Indian Journal of Critical Care Medicine. 2021;25(8):881-885. doi: 10.5005/jp-journals-10071-23916

  16. Rebic V, Masic N, Teskeredzic S, Aljicevic M, Abduzaimovic A, Rebic D. The importance of acinetobacter species in the hospital environment. Med Arch. 2018;72(3):330. doi: 10.5455/medarh.2018.72.330-334

  17. Seo HK, Hwang JH, Shin MJ, et al. Two-year hospital-wide surveillance of central line-associated bloodstream infections in a korean hospital. Journal of Korean Medical Science. 2018;33(45). doi: 10.3346/jkms.2018.33.e280

Additional Reading

By Jennifer Whitlock, RN, MSN, FN
Jennifer Whitlock, RN, MSN, FNP-C, is a board-certified family nurse practitioner. She has experience in primary care and hospital medicine.